Conventionally, a vehicle mounts a cooling device that circulates a cooling water for cooling an internal combustion engine such as an engine, between the engine or the like and a radiator. And, such cooling device is sometimes provided with a fluid control valve for controlling the flow of the cooling water for the sake of controlling the temperature of cooling water.
For instance, Patent Document 1 discloses an electronically controlled thermostat as an example of such fluid control valve. This electronically controlled thermostat disclosed in Patent Document 1 is provided with a thermo element having a piston for opening/closing a valve body, so that with transfer of the temperature of the cooling water at the exit of the radiator to an element temperature-sensitive portion of the thermo element, opening/closing of the valve body is realized. Thus, the arrangement can realize opening/closing of the valve body without provision of a sensor or the like for detecting the temperature of cooling water.
However, with the electronically controlled thermostat disclosed in Patent Document 1, the heat of cooling water heated by the engine is discharged from a heat-sensing chamber, so that there is the possibility of sufficient heat being not transferred to the element temperature-sensitive portion. In such case, delay will occur in the opening of the valve body, disadvantageously.
In order to solve the above problem, it is conceivable to employ an electromagnetic valve disclosed in Patent Document 2 as the fluid control valve. With the electromagnetic valve of Patent Document 2, a movable core is mounted inside a coil. As the movable core is moved in response to electric power supply to the coil, opening/closing of the valve is controlled. Therefore, with an arrangement for controlling the power supply to the coil according to the temperature of the fluid, there can be provided a fluid control valve having good temperature followability or sensitivity for a change in the temperature of the fluid.